Structured release liners have been used to impart air-bleedable patterns in the adhesive surface of pressure sensitive adhesive-backed films. Such release liners have included those made with a plastic (e.g., a polyester) film core having a layer of a thermoplastic polymeric material (e.g., polyethylene) laminated to at least the release side of the liner. Because of cost considerations, it has also been popular for such release liners to be made with a paper core having a structural support layer of a thermoplastic polymeric material (e.g., polyethylene) forming at least the release side of the liner. More often, the paper core is sandwiched between two layers of thermoplastic polymeric material with one layer forming the release side and the other layer forming the back side of the liner. A release material (e.g., a silicone) is typically coated on the surface of the release side. A pattern is formed in the plastic structural support layer on the release side of the liner. This pattern is suitable for forming the air-bleedable pattern in the pressure sensitive surface of the adhesive-backed film. The pattern is either formed solely in the corresponding plastic layer or, if the plastic layer is relatively thin compared to the depth of the pattern, into both the plastic layer and the core paper. For example, see Japanese Kokai Patent Applications Nos. HEI 11-323790 and HEI 9-141812, and U.S. Pat. No. 6,630,218. In either case, the plastic material structurally supports the pattern formed in the release liner. Such patterns have been formed in the plastic structural support layer by heating the thermoplastic material until it softens sufficiently to allow the desired pattern to be embossed or otherwise formed into its surface. Such release liners are often referred to as polycoated paper release liners or simply as paper release liners. It is clear that references in the prior art to paper release liners, used to impart air-bleedable patterns in pressure sensitive adhesive surfaces, are referring to such polycoated paper release liners.
The present invention is an improvement over such prior release liners, assemblies made with such release liners and the methods for making each.